Annealing Effect on Microstructure of Novel Ti Doped DLC Multilayer Films

Diamond-like films (DLC) are an exceptional engineering material with excellent performance such as high hardness, low friction coefficient, superior wear resistance and chemical inertness. However, two major problems of high internal stress and poor thermal stability have seriously limited its industrial applications. In particular, the microstructures and properties of pure DLC films are highly sensitive to high temperature. Therefore, the purpose of this study is to investigate the effect of annealing temperature on the microstructures of the as-prepared films. Ti-doped DLC multilayer films were synthesized by closed field unbalanced magnetron sputtering. The as-deposited films were annealed in the range of 200 to 800 °C. The surface morphology, phase structure and bonding structure of the films were characterized by SEM, AFM, GIXRD and Raman spectroscopy. The resulting films remained a smooth surface after annealing and maintained the nature of amorphous carbon up to 600 °C. The formed phases of graphite carbon and TiC nanocrystallines occur above 600 °C. In addition, the D- and G-bands showed a significant blue shift and the FWHMG shows a declining trend up to 600 °C. This result revealed that the films had high graphitization temperature and good thermal stability due to the formation of TiC nanocrystallines and its novel structure design containing elemental doping, multilayer structuring and functionally graded layering.